Other
hub and Currie chain drive motors, brushed and brushless, from 180 to
750 Watts are available. High capacity Sealed Lead Acid and lightweight
Lithium batteries are standard. Nickel metal-hydride batteries of varying
capacities are available by special order.

In
most states, a bicycle powered by an electric motor with less than 1
horsepower (750 Watts), that weighs less than 100 lbs., and is capable
of not more than 20 mph (unassisted, with a 170 lbs. rider over flat
terrain), is street legal as an electrically assisted bicycle.